Accurate measurement of cognitive abilities is a critical requirement for testing psychological theories of aging, as well as for making informed decisions about the mental functioning of a given person in real-world situations. Deficits in attentional processes are thought to be a central underlying factor in the decline of higher-order cognition and functional outcomes in aging individuals. Yet surprisingly little emphasis has been placed on the development of psychometric instruments with which individual differences in attentional abilities can be assessed. Without such instruments, theoretical and applied evaluations of cognitive processes and their age- or disease-related changes may be compromised. The objective of this application is to combine experimental and psychometric approaches in order to improve the measurement of selective visual attention ability in aging individuals. Three specific aims are proposed to accomplish this objective: empirical evidence will be gathered regarding (1) the components of difficulty and (2) dimensionality of attentional ability that underlies both context-free and context-specific visual search tasks, and (3) the precision of measurement obtained across ability levels within each task and the extent to which attentional abilities relate to other cognitive abilities (processing speed, primary and working memory, inhibition, and visuo-spatial ability). Explanatory latent trait modeling will be used to meet these aims. In sum, the work in this proposal will result in a better understanding of the measurement of select visual attention by exploring both the construct to be measured and the abilities of the persons to be measured. It will also result in a precursory set of instruments that can be used to continue exploring individual differences in selective visual attention. Finally, the bridging of psychometric and experimental methods as proposed here will serve as a blueprint for future similar work in other areas of cognitive processing. PUBLIC HEALTH RELEVANCE: Individual differences in attentional abilities are likely to be relevant in evaluating many different cognitive and functional outcomes in aging individuals. The removal of driving privileges, placement into assisted care facilities, and other similar concerns are serious decisions that require the utmost precision of measurement in order to minimize mis-diagnosis and mis-labeling. Thus, individual differences in attention represent an important factor to be conceptualized, measured, and explored in the context of both theoretical examinations of cognition and in everyday life. The successful incorporation of currently under-utilized psychometric methods within the domain of cognitive aging as outlined in this proposal will greatly improve the validity of future research endeavors, as well as lead to improved decision-making in applied settings with aging individuals.